For refreshable Braille displays, it has not been easy to position the cursor for advancing displayed text by one word, or one line, or one paragraph. For example, a Braille display user must move his or her hands between the Braille display and the keyboard until the desired cursor position is found. This can significantly slow the reading process. Frequently, the prior art navigation aids only allow movement of the text or cursor by only one fixed step at a time, namely, by one word at a time. Consequently, scrolling through text can be time consuming.
U.S. Pat. No. 6,163,280 shows a Braille display having a row of switches above and a row of switches below the row of Braille cells. The upper row of switches may, for example, position the displayed text and the lower row of switches may position a mouse cursor within text to be edited. The switches are designed to be operated with the same finger which is used to read the Braille cells. Consequently, the fingers must be moved from the displayed cell in order to operate the scrolling switches. The user also must touch the display cells to determine the position of the cursor.
Sliders provided with some refreshable Braille displays provide navigation speed, but have only a finite travel. Touching and moving a finger along the slider provides text navigation. For example, a six inch slider could easily navigate through a page containing 25 lines of text. Each line would require about one quarter inch of movement on the slider. But if the document has ten pages of text, each line would occupy only about 0.024 inch movement. Consequently, some degree of training and skill may be required to precisely advance the text.
It is known that a computer mouse may have a programmable navigation wheel. The navigation wheel has a mechanical detents. As the wheel is rotated between detents, a pulse is generated. It is known that the pulses may be used to advance the displayed text by a preselected number of lines. The navigation wheel also may be used to perform a programmed function when depressed, such as selecting a word or functioning as a double click of a mouse button. However, navigation wheels have not been used with Braille displays and the advantages of using a navigation wheel with a Braille display have not been appreciated.
As used herein, “text products for the vision impaired” includes not only refreshable Braille displays, but also notetakers, portable personal computer with a Braille display, and reading machines. A “notetaker” includes either a conventional keyboard or a Braille keyboard for entering data, a memory for storing entered data, and an output device. The output device may be a Braille display, or it may be in the form of an audible output device including a program for converting the stored text data to speech and either a speaker or an earphone for playing the speech. Or, the notetaker may include both a Braille display and an audible output. Vision impaired students, for example, frequently use a notetakers for taking notes in the classroom. Later the notes may be read or listened to. The notes also may be transferred to a personal computer for reviewing, editing and storage. Some notetakers are capable of using replaceable memory cards. Text such as a book may be stored on the card and the notetaker may be used for reading the text. Still another product for the vision impaired is the reading machine. Text such as a book may be stored on a tape, a CD or in a digital memory. The text is converted to audible speech. For each of these products, it has not been easy for a user to navigate or scroll through the text to a desired location.